Bioactive peptides in milk products

The physiological significance of a range of bioactive peptides produced by hydrolysis of milk proteins, and found in a number of dairy products, is reviewed. Peptides considered include: opioid peptides, which have analgesic and sedative effects; casein phosphopeptides (CPP), which have anticariogenic activity and can enhance the absorption of calcium; angiotensin I converting enzyme (ACE)-inhibitory peptides, which have antihypertensive activity; immunomodulating peptides; and antithrombotic peptides. Examples of biopeptide production in dairy products are presented and include: the formation of CPP during ripening of curd cheeses (Comte and Grana Padano); formation of a potential hypotensive peptide in Parmigiano Reggiano cheese; and the production of an opioid peptide and an ACE-inhibitory peptide in fermented milk. Analytical techniques for characterizing biopeptides are discussed, together with the effects of food processing on bioavailability of these biomolecules.